Towards phase field models of skyrmions and multiferroic domains

Seminar

Tuesday, 15.01.2019 10:00

Abstract: In this talk, I will highlight work done at FZU in the past year
regarding the topic of constructing mesoscopic models of ferroelectric
and multiferroic materials and the subsequent search for stable
skyrmions in their nanostructures. One goal of our group has been to
investigate the domain structure of the multiferroic skyrmion-lattice
host GaV4(S,Se)8. Using density-functional methods, we probe the order
parameter subspace of GaV4Se8 and parameterize an effective
thermodynamic potential useful for domain topology prediction.
Additionally for multiferroic BiFeO3, we also demonstrate that once the
energy landscape has been thoroughly explored as was done previously by
co-workers, that domain wall profiles can be predicted in agreement with
previously published DFT results. In parallel to this effort, the search
for skyrmion and skyrmion-like phases in ferroelectric nanoparticles
continues. Here, the phase field method is used to explored confined
ferroic phases of varying nanoshapes of lead titanate embedded in
dielectric media. It is shown that the directionality of an intrinsic
vortex-like core can be controlled using an applied electric field or
tunable interparticle spacings, and that the arrival of a skyrmion-like
vortex phase is universal across the entire superellipsoid shape morphology.